In industrial settings, an individual's hearing health is dependent on the amount of noise the individual is exposed to over a certain period of time. Typically, the accumulated amount of noise (e.g. dose in terms of an average noise level) and the maximum level of noise to which an individual is exposed to during the workday are strictly regulated by industry guidelines, such as the Occupational Safety and Health Administration (OSHA) in the United States.
Generally, noise data measurements may include impulse noise which relates to noise occurring for a very short duration (e.g. less than a few thousandths of a second) and continuous noise which relates to noise occurring longer in duration (e.g. extending over seconds, minutes, or hours). An example of regulating the noise data measurements may include an eight-hour time weighted average (TWA) which is the average of all levels of impulse noise and continuous noise to which an individual is exposed to during a typical eight-hour work shift. For example, the OSHA guideline/regulation for an eight-hour TWA is a maximum noise exposure of 90 dBA (decibels measured on the A scale (slow response) are generally less sensitive to very low frequencies and very high frequencies). Additionally, for individuals exposed to noise between 85-90 dBA, OSHA requires employers to initiate a hearing conservation program which includes annual hearing tests. Thus, in some instances, it may be advisable to try to keep workers on eight hour shifts under 85 dBA, to avoid the need for a hearing conservation program. Depending on the number of hours a worker is exposed to noise, the maximum noise exposure may vary. Under OSHA guidelines (which are subject to change and apply only to the United States), the permissible exposure limit (PEL) of a worker exposed to noise for, for example, 4 hours is 95 dBA and 2 hours is 100 dBA. Typically, the PEL may be determined by lookup tables or calculated based on a known exchange rate.
It is important to note that other countries may also have strict guidelines for noise exposure since noise-induced hearing loss has been and is a prevalent issue within sound industry, for example the agricultural, mining, construction, military, manufacturing, oil, and transportation industries. Often times, reducing noise exposure simply by sound-proofing and guarding machinery may not be an effective method. Additionally, sometimes wearing a hearing protection device may not be enough to prevent hearing loss since, for example, the sound-proofing material/attenuation may not provide sufficient blockage of external noise. Generally, conventional methods may focus on remedial measures taken after excessive noise exposure and may not prevent the user from experiencing hearing damage/loss/impairment. Therefore, within industry there may be a need to provide users with real-time/active feedback to ensure compliance with industry regulations/guidelines and to prevent the user from undergoing remedial measures once hearing damage has already occurred. Therefore, disclosed hearing protection device embodiments implement noise dosimetry and provide the user with real-time data (e.g. amount of time remaining before PEL of the user is reached/exceeded) to safeguard the hearing of the user (such as workers, employees, customers, etc.) against harmful and/or prolonged noise exposure.